Atmospheric rivers (ARs) can induce significant melting of sea ice as they approach the ice cover. However, due to the complex physical properties of sea ice, the specific processes within the ice pack that are responsible for its response to ARs remain poorly understood. This study aims to shed light on this question using a stand-alone sea ice model forced by observed atmospheric boundary conditions. The findings reveal that the ARs induced ice melt and hindered ice growth in the marginal seas can be attributed to a combination of thermodynamic and dynamic processes. The AR-wind transports ice floes from the marginal seas back to the central Arctic dynamically, resulting in a thickening of the ice cover in that region. Among the thermodynamic processes, reduced congelation growth (54-56%), enhanced basal melting (17-26%), and inhibited snow-ice formation (11-21%) play major roles in the sea ice loss in the marginal seas.

In recent decades, Arctic sea ice coverage experienced a drastic decline in winter, when sea ice is expected to recover following the melting season. Using observations and climate model simulations, we found a robust frequency increase in atmospheric rivers (ARs, intense corridors of moisture transport) over Barents-Kara Seas and the neighboring central Arctic (ABK) in early winter. The extensive moisture carried by more frequent ARs has intensified surface downward longwave radiation and liquid rainfall, caused stronger melting of thin, fragile ice cover, and slowed the seasonal recovery of sea ice, contributing to the sea ice cover decline in ABK. A series of model ensemble experiments suggests that, in addition to a uniform AR increase in response to anthropogenic forcing, the contribution of tropical Pacific variability is indispensable in the observed Arctic AR changes. These findings have significant implications for understanding the rapidly changing Arctic hydroclimate and the cryosphere.

The Asian monsoon anticyclone (AMA) exhibits a trimodal distribution of sub-vortices and the western Pacific is one of the preferred locations. Amplification of the western Pacific anticyclone (WPA) is often linked with eastward eddy shedding from the AMA, although the processes are not well understood. This study investigates the dynamics driving eastward eddy shedding associated with the emergence of the WPA in the upper troposphere and lower stratosphere on synoptic scales. Using reanalysis data during 1979 to 2019, our composite analysis reveals that amplified WPA events are closely related to the upstream Silk Road (SR) wave-train pattern over mid-latitude Eurasia as identified in previous studies. The quasi-stationary eastward propagating eddies result from baroclinic excitation along the westerly jet, as identified by coherent eddy heat fluxes and relaxation of the low-level temperature gradient. The upper-level westerly jet is important in determining the longitudinal phase-locking of wave trains, which are anchored and amplify near the jet exit. Occasionally enhanced convection near the Philippines also triggers anticyclonic eddies that propagate upward and northeastward via the Pacific-Japan (PJ) pattern, forming the WPA in the upper troposphere. Correlation analysis suggests that the SR and PJ mechanisms are not physically correlated.